The invention is generally directed to an equalizer for a suspension system used in vehicles or trailers having multiple axles, e.g., tandem or tri-axles with double eye springs, such as recreational vehicles, mobile homes and light trailers of all types.
A prior art suspension system 20 currently used on trailers incorporates an equalizer 22 such as the one shown in FIG. 1. The suspension system 20 is mounted on a frame 24 of the left side of the trailer and another, identical suspension system 20 is mounted on the frame 24 of the right side of the trailer. Only the suspension system 20 mounted on the frame 24 of the left side of the trailer is shown in FIG. 1. The suspension system 20 includes the equalizer 22, a front leaf spring 26, a rear leaf spring 28, a front shackle or link 30 and a rear shackle or link 32.
The equalizer 22 is generally triangular in shape, having a first end corner 34, a second end corner 36 and a third end corner 38. Other equalizers of the prior art may be curved rather than triangular in shape. The equalizer 22 is generally formed of cast iron and is rigid. The first end corner 34 of the equalizer 22 is attached to a center frame hangar 40, which depends from the frame 24 of the trailer, at a point A. The second end corner 36 of the equalizer 22 is pivotally mounted to a first end 42 of the front shackle 30 at a point B. The third end corner 38 of the equalizer 22 is pivotally mounted to a first end 44 of the rear shackle 32 at a point C.
A second end 46 of the front shackle 30 is pivotally mounted to a rear end 48 of the front leaf spring 26 at a point D. A front end 50 of the front leaf spring 26 is attached to the frame 24 of the trailer at a point E.
A second end 52 of the rear shackle 32 is pivotally mounted to a front end 54 of the rear leaf spring 28 at a point F. A rear end 56 of the rear leaf spring 28 is attached to the frame 24 of the trailer at a point G.
A front axle 58 is positioned on the forward leaf spring 26 generally equidistantly between point D and point E. A rear axle 60 is positioned on the rear leaf spring 28 generally equidistantly between point F and point G.
To the extent possible, road shock and vibrations from tires of the trailer are transferred to the front and rear axles 58, 60, and are absorbed by the front and rear leaf springs 26, 28, respectively. Points A, E and G are the contact points through which the road shock is passed to the frame 24. The equalizer 22 basically has only one purpose for being including in the suspension system 20, which is to equalize the weight on both the front and rear axles 58, 60 as the tires pass over uneven terrain. For example, an upward motion of the front leaf spring 26 results in a downward motion of the rear leaf spring 28.
The equalizer 22, however, is not configured to dampen or absorb the harsh shocks or vibrations coming off the rear end 48 of the front leaf spring 26 and the front end 54 of the rear leaf spring 28 proximate to the center frame hangar 40, which would thus allow for a “softer” ride. The equalizer 22 of the prior art has been in use without a single design change for at least the past forty (40) years.
Thus, there is a need for an equalizer which overcomes the aforementioned disadvantages. The present invention provides such an equalizer. Features and advantages of the present invention will become apparent upon a reading of the attached specification, in combination with a study of the drawings.